Melanin is produced by Cryptococcus neoformans, an organism causing life-threatening infections in an estimated 10% of AIDS patients. A laccase enzyme has been found to be responsible for conversion of catechols (diphenols), such as dopa and dopamine, into a melanin-like pigment. Studies are under way to correlate the production of melanin and virulence with age of the infection in mouse cell cultures. Interest is in when melanin is first formed and when it can first be detected.